Was it a Certified BMW paint facility ?
https://www.bodyshopbusiness.com/off...match-a-color/
" Choose the right size metallic flakes. When matching metallic colors, always be sure that the metallic flake is the proper size. You can actually have a paint color match, but it’ll appear differently than the car because of a mis-matched metallic. Coarser metallic makes the paint look darker, while a finer metallic makes the paint look lighter. When choosing an alternate formula, choose the one with the right metallic that matches your vehicle. "
Have no opinion if you should complain or not. BMW M850 certainly isn't a vehicle you have an apprentice work on.